Global warming due to human-induced increments in atmospheric concentrations of greenhouse gases
(GHG) is one of the most debated topics among environmentalists and politicians worldwide. In this paper
we assess a novel source of GHG emissions emerged following a controversial policy decision. After the
outbreak of bovine spongiform encephalopathy in Europe, the sanitary regulation required that livestock
carcasses were collected from farms and transformed or destroyed in authorised plants, contradicting not
only the obligations of member states to conserve scavenger species but also generating unprecedentedGHG
emission. However, how much of this emission could be prevented in the return to traditional and natural
scenario in which scavengers freely remove livestock carcasses is largely unknown. Here we show that, in
Spain (home of 95% of European vultures), supplanting the natural removal of dead extensive livestock by
scavengers with carcass collection and transport to intermediate and processing plants meant the emission
of 77,344 metric tons of CO2 eq. to the atmosphere per year, in addition to annual payments of ca. $50
million to insurance companies. Thus, replacing the ecosystem services provided by scavengers has not only
conservation costs, but also important and unnecessary environmental and economic costs